view release on metacpan or  search on metacpan

unzip-6.0/extract.c  view on Meta::CPAN

    return error;

} /* end function memextract() */





/*************************/
/*  Function memflush()  */
/*************************/

int memflush(__G__ rawbuf, size)
    __GDEF
    ZCONST uch *rawbuf;
    ulg size;
{
    if (size > G.outsize)
        /* Here, PK_DISK is a bit off-topic, but in the sense of marking
           "overflow of output space", its use may be tolerated. */
        return PK_DISK;   /* more data than output buffer can hold */



    memcpy((char *)G.outbufptr, (char *)rawbuf, (extent)size);
    G.outbufptr += (unsigned int)size;
    G.outsize -= size;
    G.outcnt += size;

    return 0;

} /* end function memflush() */





#if (defined(VMS) || defined(VMS_TEXT_CONV))

/************************************/
/*  Function extract_izvms_block()  */
/************************************/

/*
 * Extracts block from p. If resulting length is less than needed, fill
 * extra space with corresponding bytes from 'init'.
 * Currently understands 3 formats of block compression:
 * - Simple storing
 * - Compression of zero bytes to zero bits
 * - Deflation (see memextract())
 * The IZVMS block data is returned in malloc'd space.
 */
uch *extract_izvms_block(__G__ ebdata, size, retlen, init, needlen)
    __GDEF
    ZCONST uch *ebdata;
    unsigned size;
    unsigned *retlen;
    ZCONST uch *init;
    unsigned needlen;
{
    uch *ucdata;       /* Pointer to block allocated */
    int cmptype;
    unsigned usiz, csiz;

    cmptype = (makeword(ebdata+EB_IZVMS_FLGS) & EB_IZVMS_BCMASK);
    csiz = size - EB_IZVMS_HLEN;
    usiz = (cmptype == EB_IZVMS_BCSTOR ?
            csiz : makeword(ebdata+EB_IZVMS_UCSIZ));

    if (retlen)
        *retlen = usiz;

    if ((ucdata = (uch *)malloc(MAX(needlen, usiz))) == NULL)
        return NULL;

    if (init && (usiz < needlen))
        memcpy((char *)ucdata, (ZCONST char *)init, needlen);

    switch (cmptype)
    {
        case EB_IZVMS_BCSTOR: /* The simplest case */
            memcpy(ucdata, ebdata+EB_IZVMS_HLEN, usiz);
            break;
        case EB_IZVMS_BC00:
            decompress_bits(ucdata, usiz, ebdata+EB_IZVMS_HLEN);
            break;
        case EB_IZVMS_BCDEFL:
            memextract(__G__ ucdata, (ulg)usiz,
                       ebdata+EB_IZVMS_HLEN, (ulg)csiz);
            break;
        default:
            free(ucdata);
            ucdata = NULL;
    }
    return ucdata;

} /* end of extract_izvms_block */





/********************************/
/*  Function decompress_bits()  */
/********************************/
/*
 *  Simple uncompression routine. The compression uses bit stream.
 *  Compression scheme:
 *
 *  if (byte!=0)
 *      putbit(1),putbyte(byte)
 *  else
 *      putbit(0)
 */
static void decompress_bits(outptr, needlen, bitptr)
    uch *outptr;        /* Pointer into output block */
    unsigned needlen;   /* Size of uncompressed block */
    ZCONST uch *bitptr; /* Pointer into compressed data */
{
    ulg bitbuf = 0;
    int bitcnt = 0;

#define _FILL   {       bitbuf |= (*bitptr++) << bitcnt;\
                        bitcnt += 8;                    \
                }

    while (needlen--)
    {
        if (bitcnt <= 0)
            _FILL;

        if (bitbuf & 1)
        {
            bitbuf >>= 1;
            if ((bitcnt -= 1) < 8)
                _FILL;
            *outptr++ = (uch)bitbuf;
            bitcnt -= 8;
            bitbuf >>= 8;
        }
        else
        {
            *outptr++ = '\0';
            bitcnt -= 1;
            bitbuf >>= 1;
        }
    }
} /* end function decompress_bits() */

#endif /* VMS || VMS_TEXT_CONV */